Flood prioritization of Sarbaz river sub-basins using SWAT model

Flood is one of the most important threats to human society, which has increased in recent decades with the increase in population and climate change. Therefore, studying the features of the basins that are related to the level of flooding can help to properly manage this risk. Nowadays, several methods such as morphological characteristics, This research was carried out using SWAT hydrological model in 21 sub-basins of Sarbaz watershed located in Sistan and Baluchistan province. After preparing the parameters and input data, while considering two years for warming, the model was recalibrated for a 17-year period from 1999 to 2016 and then validated during a five-year period from 2017 to 2021. The results obtained in the calibration stage were NS=0.76 and R2=0.86 and in the validation stage NS=0.56 and R2=0.58. The initial curve number parameter for medium humidity conditions and the alpha parameter in the return flow had the greatest effect in the sensitivity analysis. The results showed that sub-basin 20 with an average runoff height of 2.46 was ranked first and sub-basin 10 with a runoff height of 0.06 was ranked last. Based on the explanation and Nash-Sutcliffe, it can be concluded that the model has performed well in the simulation of Sarbaz watershed and can be used for modeling in the basin. Flood control by prioritizing flooding in sub-basins and by implementing management measures to improve pasture coverage and build watershed structures in the Sarbaz river basin has reduced the amount of flood discharge and prevented sudden damages.